U.S. patent number 9,823,147 [Application Number 14/890,347] was granted by the patent office on 2017-11-21 for method and system for determining the plunger load of a baler.
This patent grant is currently assigned to CNH Industrial America LLC. The grantee listed for this patent is CNH Industrial America LLC, INDUCT BVBA, KATHOLIEKE UNIVERSITEIT LEUVEN. Invention is credited to Tom Coen, Kenny Nona, Didier Verhaeghe.
United States Patent |
9,823,147 |
Verhaeghe , et al. |
November 21, 2017 |
Method and system for determining the plunger load of a baler
Abstract
A method and adapted electronic systems for determining a value
representative for or an estimate of the load on a plunger of a
baler for harvested agricultural material includes obtaining the
speed of movement of a drive element for the plunger, followed by
determining the estimate of or value representative for the load on
the plunger based upon the obtained speed of movement of the drive
element.
Inventors: |
Verhaeghe; Didier (Ieper,
BE), Nona; Kenny (Kessel-Lo, BE), Coen;
Tom (Zemst, BE) |
Applicant: |
Name |
City |
State |
Country |
Type |
CNH Industrial America LLC
KATHOLIEKE UNIVERSITEIT LEUVEN
INDUCT BVBA |
New Holland
Leuven
Heverlee-Leuven |
PA
N/A
N/A |
US
BE
BE |
|
|
Assignee: |
CNH Industrial America LLC (New
Holland, PA)
|
Family
ID: |
48917265 |
Appl.
No.: |
14/890,347 |
Filed: |
May 8, 2014 |
PCT
Filed: |
May 08, 2014 |
PCT No.: |
PCT/EP2014/059487 |
371(c)(1),(2),(4) Date: |
November 10, 2015 |
PCT
Pub. No.: |
WO2014/180965 |
PCT
Pub. Date: |
November 13, 2014 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20160109309 A1 |
Apr 21, 2016 |
|
Foreign Application Priority Data
|
|
|
|
|
May 10, 2013 [BE] |
|
|
2013/0327 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A01F
15/0825 (20130101); A01F 15/042 (20130101); A01F
15/0841 (20130101); B62D 5/04 (20130101); G01L
5/00 (20130101) |
Current International
Class: |
G01L
5/00 (20060101); A01F 15/08 (20060101); A01F
15/04 (20060101); B62D 5/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pipala; Edward J
Attorney, Agent or Firm: Zacharias; Peter K. Sheldrake;
Patrick M.
Claims
The invention claimed is:
1. A method for determining a value representative for a load on a
plunger of a baler for forming bales of agricultural material, the
baler comprising the plunger and a drive system for the plunger,
the drive system comprising a drive element, the method comprising
the steps of: obtaining a speed of movement of the drive element of
the drive system for the plunger; and determining an estimate of
the load on the plunger based upon the obtained speed of movement
of the drive element by use of a predetermined relationship between
the speed of movement of the drive element and the load on the
plunger.
2. The method according to claim 1, wherein the predetermined
relationship is a predetermined function between the load on the
plunger and the speed of movement of the drive element.
3. The method according to claim 1, wherein the predetermined
relationship is selected in accordance with obtained agricultural
material characteristics of the agricultural material being baled
by the baler.
4. The method according to claim 1, further comprising the step of:
determining whether the plunger is operating under a first
condition wherein the plunger is moving and compressing
agricultural material in the baler or under a second condition
wherein the plunger is only moving agricultural material in the
baler without compressing the agricultural material in the baler;
wherein the predetermined relationship is selected in accordance
with the determined condition.
5. The method according to claim 1, wherein the drive system for
the plunger comprises a first subsystem and a second subsystem,
wherein the first subsystem is capable of obtaining an external
driving force and adapted for directing a portion of the external
driving force to the second subsystem specific for the plunger, and
wherein the drive element is part of the second subsystem.
6. The method according to claim 1, further comprising the step of:
obtaining a signal indicative of whether at least one other bale
component that is operatively connected to the drive system is
actually driven by the drive system when the step of determining
the load of the plunger is performed, wherein the step of
determining the load of the plunger is further based on the
indicative signal.
7. The method according to claim 1, whereby the predetermined
relationship is based on a set of differential equations describing
at least dynamics of the plunger and dynamics of the drive system,
the equations including the load on the plunger and a rate of
change of the speed of movement of the drive element.
8. The method according to claim 7, wherein a model-based estimator
is used for determining a value representative of the load of the
plunger, the model being based on the set of differential
equations.
9. The method according to claim 1, wherein the drive system
further comprises a flywheel operatively connected to the plunger,
and wherein the drive element is the flywheel.
10. A method for use in controlling a load on a plunger of a baler,
the method comprising the steps of: obtaining a speed of movement
of a drive element of a drive system for the plunger; determining a
value representative of the load on the plunger based upon the
obtained speed of movement of the drive element by use of a
predetermined relationship between the speed of movement of the
drive element and the load on the plunger; and determining a
control signal for controlling the load on a plunger of a baler
based on the determined value representative of the load on the
plunger.
11. The method according to claim 10, further comprising a step of
controlling the load on the plunger using at least one controllable
element, steered by an actuator, by applying the determined control
signal to the actuator of the controllable element.
12. A control system for a baler comprising a plunger and a driving
system having at least one drive element for driving the plunger,
the system comprising an electronic device configured for
determining a value representative of a load on the plunger of the
baler, the electronic device configured for obtaining a speed of
movement of the at least one drive element; wherein the electronic
device comprises a data storage configured for storing data about a
predetermined relationship between the speed of movement of the at
least one drive element and the load on the plunger; and wherein
the electronic device is further configured for determining the
value representative of the load on the plunger based upon the
obtained speed of movement of the at least one drive element by use
of the stored predetermined relationship between the speed of
movement of the at least one drive element and the load on the
plunger.
13. The system according to claim 12, further comprising a sensor,
operatively connected to the electronic device, the sensor for
measuring a speed of movement of the at least one drive element and
providing the speed of movement of the at least one drive element
to the electronic device.
14. The system according to claim 12, wherein the electronic device
is further configured for determining a control signal for
controlling the load on the plunger of the baler, wherein the data
storage is further configured for storing a reference maximum load
of the plunder, and wherein the electronic device is further
configured for determining a control signal based on the determined
value representative of the load on the plunger by use of a
comparator for comparing the determined value representative of the
load of the plunger with the stored reference maximum load of the
plunger.
15. The system according to claim 14, wherein the electronic device
is further configured for controlling the load on the plunger of
the baler.
Description
This application is the US National Stage filing of International
Application Serial No. PCT/EP2014/059487 filed on May 8, 2014 which
claims priority to Belgian Application BE2013/0327 filed May 10,
2013, each of which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
The invention relates to methods and systems used in balers for
forming bales of agricultural material, more in particular methods
and systems for determining the plunger load and use of such
methods and systems for controlling such balers.
BACKGROUND OF THE INVENTION
An agricultural baler is a trailed machine, typically towed behind
agricultural vehicles such as tractors, used in agriculture for the
purpose of forming bales of agricultural materials, such as straw,
hay, silage or other biomass, produced during a harvesting or
mowing operation. A baler typically comprises an infeed through
which biomass is introduced into a bale-forming chamber. In the
bale-forming chamber the biomass is generally compressed or
otherwise treated to form bales. The completed bales are tied with
twine or a similar lineal object or are packaged in another way to
make them self-supporting. The bales are subsequently ejected by
means of a discharge mechanism.
Referring to the drawings, FIG. 1 shows agricultural baler 600
comprising a frame 512 which is equipped with a forwardly extending
tongue 514 at its front end with hitch means (not shown) for
coupling the baler 600 to a towing tractor. A pick-up assembly 513
lifts windrowed agricultural material off the field as the baler
600 is travelled there over and delivers such material into the
front end of a rear ward and upwardly curved, charge-forming feeder
duct 515. The duct 515 communicates at its upper end with an
overhead, fore-and-aft extending bale-forming chamber 516 into
which agricultural material charges are loaded by a cyclically
operating stuffer mechanism 517. A continuously operating packer
mechanism 519 at the lower front end of the feeder duct 515
continuously feeds and packs material into the duct 515 as to cause
charges of the agricultural material to take on and assume the
internal configuration of the duct 515 prior to periodic engagement
by the stuffer 517 and insertion up into the bale-forming chamber
516. The feeder duct 515 may be equipped with means (not
illustrated) for establishing whether a complete charge has been
formed therein and operating the stuffer mechanism 517 in response
thereto. Each action of the stuffer mechanism 517 introduces a
"charge" or "flake" of agricultural material from the duct 515 into
the chamber 516. A plunger 562 reciprocates in a fore-and-aft
direction within the bale-forming chamber 516. Biomass fed via the
feeder duct 515 is thereby compacted, e.g. compressed or otherwise
treated, so as to form bales in the above-described operation of
the agricultural baler 600. Rectangular bales are formed. The
completed bales are tied with twine or a similar lineal object to
make them self-supporting, for example for shipping and storage.
Once tied, the bales are discharged from the rear end of the
bale-forming chamber 516 onto a discharge in the form of a chute,
generally designated 520.
In the art the load on the plunger is either measured by load
sensors or sensors that measure deformation of the bale chamber.
Those sensors are expensive or require a complex set-up with
careful calibration because of the high load involved. Furthermore
since here the balers comprise of large structural elements of
which the production tolerances are difficult to control, the
required high accuracy measurements as necessary for a baler
control system, are difficult to achieve.
SUMMARY OF THE INVENTION
It is an object of embodiments of the present invention to provide
methods and systems used in balers for forming bales of
agricultural material, more in particular methods and systems for
determining the plunger load (i.e. the force exerted on the
plunger) and use of such methods and systems for controlling such
balers, which are simple, cheap and/or robust.
The above objective is accomplished by methods and systems
according to embodiments of the present invention.
Particular and preferred aspects of the invention are set out in
the accompanying independent and dependent claims. Features from
the dependent claims may be combined with features of the
independent claims and with features of other dependent claims as
appropriate and not merely as explicitly set out in the claims.
In a first aspect of the invention a method for determining a value
representative for the load (e.g. an estimate of the load or a
value proportional to the load) on a plunger of a baler is
provided, whereby the baler at least comprises a drive system for
the plunger, the drive system comprising at least one moving drive
element. The method comprises a step of obtaining (e.g. receiving)
the speed of movement of the drive element, followed by determining
the estimate of or value representative for the load on the plunger
based upon the obtained speed of movement of the drive element by
use of a predetermined relationship between this speed of movement
of the drive element and the load on the plunger.
In a first embodiment of the first aspect, the predetermined
relationship is a function or a set of (one or multi-dimensional)
functions (e.g. a linear function or any other polynomial fitted
through the available data) between the load on the plunger and the
speed of movement of the drive element.
In an embodiment of the first aspect, the predetermined
relationship is selected in accordance with obtained (e.g. input by
the operator or on-line measured values like agricultural material
humidity) agricultural material characteristics of the agricultural
material being baled by the baler. This is advantageous as it
permits to take into account the nature of the baled agricultural
material, which leads to more accurate load values.
In an embodiment of the first aspect the method may further
comprise of a step of determining (e.g. from measurements on the
bale chamber of the baler) whether the plunger is operating under a
first condition (called active cycles) wherein the plunger is
moving and compressing agricultural material in the baler or under
a second condition (called passive cycles) wherein the plunger is
only moving new agricultural material in the baler without
compressing the new agricultural material therein; and the
predetermined relationship is then selected in accordance with the
determined condition. This is advantageous as it permits to take
into account the nature of the cycle within the baler, which leads
to more accurate load values.
In an embodiment of the first aspect of the invention the drive
system for the plunger comprises a first subsystem, capable of
obtaining an external driving force and adapted for directing a
portion of this external driving force to a second subsystem
specific for the plunger and the method is then further
characterized in that the drive element is part of the second
subsystem.
In another embodiment of the invention the drive system is
operatively connected to at least one other baler component (e.g.
the stuffer or the knotter) and the method then further comprises
obtaining a signal indicative on whether the one (or more) other
bale component(s) is (are) actually driven by the drive system at
the time instance of determining the load of the plunger and the
method is further characterized in that the step of determining the
load of the plunger takes into account this indicative signal. This
is advantageous as it permits to take into account the reparation
of power amongst various baler components, which leads to more
accurate load values.
In another embodiment of the invention the predetermined
relationship is based on one or more differential equations (e.g. a
set of first order differential equations) describing at least the
dynamics of the plunger, the second drive sub-system, and
optionally even a model of the compression behavior of the
agricultural material, these equations including the load on the
plunger and the rate of change of the speed of movement of the
drive element.
In another embodiment of the first aspect, a model-based estimator
is used for determining the value representative for or an estimate
of the load of the plunger, whereby the model is based on the (set
of) differential equation(s).
In another embodiment of the invention the second drive sub-system
comprises a flywheel, operatively connected to the plunger, and the
drive element (the speed of which is used for the determining the
plunger load) is purposely chosen to be the flywheel. This is
advantageous as speed measurements on the flywheel are accurate and
easily performed, and therefore permit more accurate load
estimates.
In a second aspect of the present invention, a method for
determining a control signal for controlling the load on a plunger
of a baler is provided, the method comprising the steps of
obtaining a value representative for or an estimate of the load on
the plunger determined in accordance with any of the methods
disclosed above and further determining a control signal based on
the obtained value representative for or an estimate of the load on
the plunger (e.g. by comparing the obtained estimate with a
reference maximum load of the plunger).
In a third aspect of the present invention, a method is provided
for controlling the load on a plunger of a baler with at least one
controllable element for controlling said load, steered by an
actuator, the method comprising the steps of determining a control
signal; followed by applying the control signal to the actuator of
the controllable element.
These second and third aspects are advantageous as they permit to
keep load automatically at a proper level.
In a fourth aspect of the invention a system used in a baler is
provided, the system comprising a first electronic device for
determining a value representative of or an estimate of the load on
a plunger of the baler driven by a drive system with at least one
drive element, the first electronic device comprising a means for
obtaining the speed of movement of the drive element; a storage
means for storing data (parameters) about a predetermined
relationship between the speed of movement of the drive element and
the load on the plunger; and a computation means for determining
the value representative of or the estimate of the load on the
plunger based upon the obtained speed of movement of the drive
element by use of the stored predetermined relationship between
this speed of movement of the drive element and the load on the
plunger.
In an embodiment of this fourth aspect of the invention further a
sensor, operatively connected to the first electronic device and
used for measuring the speed of movement of the drive element, is
provided.
In a further embodiment thereof the system is further adapted for
determining a control signal for controlling the load on a plunger
of a baler, the system comprising a second electronic device
comprising a storage means for storing a reference maximum load of
the plunger and computation means for determining a control signal
based on the obtained value representative for or an estimate of
the load on the plunger by use of a comparator for comparing the
obtained value representative of or an estimate of the load of the
plunger with the stored reference maximum load of the plunger.
In yet a further embodiment thereof the system is further being
adapted for controlling the load on a plunger of a baler as the
system comprises one controllable element of the baler for
controlling the load thereof; and an actuator, operatively
connected to the controllable element for steering in accordance
with the control signal.
In a further aspect, the present invention relates to a computer
program product that, when executed on computing means, provides
instructions for executing any one method of the first three
aspects of the present invention.
For purposes of summarizing the invention and the advantages
achieved over the prior art, certain objects and advantages of the
invention have been described herein above. Of course, it is to be
understood that not necessarily all such objects or advantages may
be achieved in accordance with any particular embodiment of the
invention. Thus, for example, those skilled in the art will
recognize that the invention may be embodied or carried out in a
manner that achieves or optimizes one advantage or group of
advantages as taught herein without necessarily achieving other
objects or advantages as may be taught or suggested herein.
The above and other aspects of the invention will be apparent from
and elucidated with reference to the embodiment(s) described
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described further, by way of example,
with reference to the accompanying drawings, in which:
FIG. 1 shows a general outline of a baler (600) with a bale-forming
chamber 516, a cyclically operating stuffer mechanism 517 and a
plunger 562.
FIG. 2 shows a schematic view of an entire baler system according
to an embodiment of the present invention.
FIG. 3 shows a flow chart of an embodiment of the invention wherein
a control signal to be applied to at least one controllable element
in the baler is determined.
FIG. 4 shows a more detailed view on the flywheel (403) and plunger
(410) interaction in the drive system (400).
FIG. 5 shows in the top graph measurements of the rotational speed
(e.g. derived either from the knotter operations or from the
flywheel) as a function of the plunger position while the bottom
graph shows measurement of the force on the plunger as a function
of the plunger position.
FIG. 6 shows the speed or velocity of the flywheel determined from
the operation of the knotter (without filtering).
FIG. 7 shows the speed of the flywheel in function of the load on
the plunger, depending on type of cycle (active, passive) and
measured for two different types of agricultural material, wheat
straw in Mechterstadt and wheat straw in Spain, respectively. The
linear correlation between those is represented by the straight
lines (700, 710, 720, and 730).
FIG. 8 shows a flow chart of an embodiment of the present invention
wherein at least two predetermined relationships are used, and one
is selected depending on the condition of an active or passive
cycle.
FIG. 9 shows a flow chart of an embodiment of the present invention
based on an estimator based on a dynamic model of the drive
system.
FIG. 10 shows a processing system including the instructions to
implement aspects of the methods according to embodiments of the
present invention.
The drawings are only schematic and are non-limiting. In the
drawings, the size of some of the elements may be exaggerated and
not drawn on scale for illustrative purposes. The dimensions and
the relative dimensions do not necessarily correspond to actual
reductions to practice of the invention.
Any reference signs in the claims shall not be construed as
limiting the scope.
In the different drawings, the same reference signs refer to the
same or analogous elements.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described with respect to particular
embodiments and with reference to certain drawings but the
invention is not limited thereto but only by the claims.
It is to be noticed that the term "comprising", used in the claims,
should not be interpreted as being restricted to the means listed
thereafter; it does not exclude other elements or steps. It is thus
to be interpreted as specifying the presence of the stated
features, integers, steps or components as referred to, but does
not preclude the presence or addition of one or more other
features, integers, steps or components, or groups thereof. Thus,
the scope of the expression "a device comprising means A and B"
should not be limited to devices consisting only of components A
and B. It means that with respect to the present invention, the
only relevant components of the device are A and B.
Reference throughout this specification to "one embodiment" or "an
embodiment" means that a particular feature, structure or
characteristic described in connection with the embodiment is
included in at least one embodiment of the present invention. Thus,
appearances of the phrases "in one embodiment" or "in an
embodiment" in various places throughout this specification are not
necessarily all referring to the same embodiment, but may.
Furthermore, the particular features, structures or characteristics
may be combined in any suitable manner, as would be apparent to one
of ordinary skill in the art from this disclosure, in one or more
embodiments.
Similarly it should be appreciated that in the description of
exemplary embodiments of the invention, various features of the
invention are sometimes grouped together in a single embodiment,
figure, or description thereof for the purpose of streamlining the
disclosure and aiding in the understanding of one or more of the
various inventive aspects. This method of disclosure, however, is
not to be interpreted as reflecting an intention that the claimed
invention requires more features than are expressly recited in each
claim. Rather, as the following claims reflect, inventive aspects
lie in less than all features of a single foregoing disclosed
embodiment. Thus, the claims following the detailed description are
hereby expressly incorporated into this detailed description, with
each claim standing on its own as a separate embodiment of this
invention.
Furthermore, while some embodiments described herein include some
but not other features included in other embodiments, combinations
of features of different embodiments are meant to be within the
scope of the invention, and form different embodiments, as would be
understood by those in the art. For example, in the following
claims, any of the claimed embodiments can be used in any
combination.
Embodiments of the present invention provide for simple, cheap and
robust methods and systems, to be used in balers, for determining
the plunger load. Other embodiments relate to the use of such
methods and systems for controlling such balers for various control
objectives such as avoiding overload of the plunger (avoiding
breakdown) and/or on-line steering of the density of the bales. In
embodiments, the methods and systems presented may make use of an
indirect way (instead of using direct measurement via e.g. a load
sensor or a deformation sensor) of determining the plunger load by
deriving from a measurement from another element of the baler a
value representative for or an estimate of the load on the plunger.
In one embodiment, speed of the flywheel is measured for
determining the plunger load. A measurement at the flywheel
indicates the total torque, required by the baler, which indicates
the load of the machine together with the drive of all other
systems. It is therefore a measure for instance for the load on the
shear bolt of the machine. Alternative sensors are strain gauges on
the baler frame, on the beam perpendicular to the driving direction
or on the beam parallel to the driving direction.
For avoiding difficult to calibrate and complex set-ups the methods
and systems presented use a measurement of a state of a drive
element within the drive system of the plunger, e.g. the speed or
velocity of such drive element. Moreover the invention describes
the purposeful selection of the drive element to be chosen (e.g.
the flywheel as it is less sensitive to disturbance from the
activation of auxiliary functions like the stuffer and the knotter)
in order to achieve a reliable representative value or estimate.
The invention also describes how other signals (like the type of
operation cycle, whether other auxiliary functions or components of
the baler like knotter and stuffer are active or not, agricultural
material characteristics) can be taken into account to increase the
reliability of the methods presented.
To be able to determine or compute a value representative for or an
estimate of the load on the plunger from another measurement (e.g.
the speed of a drive element), a relationship between those must be
established. Such relationship can be determined by measuring both
the to-be estimated value and the other measurement and find a
correlation between those (or mathematically manipulated
derivatives thereof). Finding such relationship can be based on
mathematical modeling of the behavior of the system under study
(here the plunger--drive system interactions).
An example is given in FIG. 5 showing measurements of the
rotational speed Vr (derived for instance from the knotter
operations (crosses, graph 50) or from the flywheel (plain line,
graph 52)) as a function of the plunger position X, and the
measurement of the force (load) F on the plunger (as measured by
two different sensors s1 and s2) as a function of the plunger
position X. The vertical plain lines in the graphs indicate the
start of compression (around 1.1 m along the X axis). It is clear
that higher forces are observed when the rotational speed drops, so
a correlation between force or load on the plunger and speed of an
element of the drive system (e.g. the flywheel or knotter) can be
determined FIG. 6 shows also a relation between the most rear point
of the plunger (represented by the vertical line and the star
approximately every 1.3 seconds), where the maximum load is
expected, and velocity changes, derived from different elements, in
particular the flywheel (dashed line, graph 66), being part of the
plunger drive system but also an alternative using measurements on
the knotter, optionally after use of (low pass) filtering or
averaging (see graph 65 for the knotter and graph 66 for the
flywheel). The most rear point (or distal position) of the plunger
corresponds to the situation in FIG. 4 where the angle between L1
and L2 is 180.degree.. FIG. 4 further shows a driving element 403
in a gearbox 419, a crank comprising two arms 475, 476 with
respective lengths L1 and L2, and a plunger 410. A first arm 475,
having a length L1, is attached by a first extremity to the driving
element 403 and by a second extremity to a second arm 476. The
second arm 476, having a length L2, is attached by a first
extremity to the first arm 475 and by a second extremity to the
plunger 410. L3 is the vertical distance between the first
extremity of the first arm 475 and the second extremity of the
second arm 476. X is the direction along which the location of the
plunger 410 is measured.
As indicated in FIG. 7, correlations represented by the straight
lines 700, 710, 720, and 730 between the speed and force values can
be determined. The circles indicated in regions 70 and 71 represent
the situation where the strokes are active while the crosses
indicated in regions 72 and 73 represent the situation where the
strokes are passive. It is obvious that instead of a first order
relationship (straight line) also more complicated functions
(higher order polynomials or other techniques for fitting curves
like neural networks, spline functions or other) can be used to
represent or model the relationship.
We now refer to FIGS. 2 and 3. FIG. 2 shows a schematic view of an
entire bale system with the baler 420 with its internal bale
forming chamber, the stuffer 450, a knotter 460, the plunger 410
and its reciprocating movement 411 and the crop and bale movement
direction 490. Also shown is the plunger drive system 400 with a
first 401 and second 402 sub-drive system. A system or electronic
device 430 for determining at least one control signal 405 is
illustrated. This system or electronic device 430 for determining
at least one control signal 405 comprises a system or electronic
device 431 for determining a value 406 representative for (e.g. an
estimate of) the load on the plunger 410, a system or electronic
device 417 for determining a value 408 representative of the
maximum load determined by system or device 431, a system or
electronic device 418 for comparing a reference maximum load 409
with the value 408 representative of the maximum load determined by
the system or device 431. The bale system comprises at least one
controllable element 470 of the baler, inside the bale chamber (for
controlling the load) and its actuator 440, fed by the control
signal 405. A possible realization of the second drive sub-system
402 is with a flywheel 403 driving the plunger 410, and a sensor
404 measuring the speed 416 of the flywheel 403. A means 480 is
provided for measuring within the bale chamber the current cycle
type (active or passive) 407 of the baler 420. Also represented are
a signal 414 of the operational state of the stuffer, a signal 415
for the operational state of the knotter, and a signal 412
reflecting characteristics of the agricultural material, said
signals being fed to the system or electronic device 430.
Once the relationship is determined (e.g. as illustrated in FIG.
7), a method for determining a value 406 representative for or an
estimate of the load on a plunger 410 of a baler 420, can be
proposed with a step of obtaining or measuring or sensing 10 the
speed or velocity of movement 416 of the drive element 403; and
determining 20 (or computing) the estimate 406 of the load on the
plunger 410 based on the obtained speed of movement 416 of the
drive element 403 by use of a predetermined relationship 220
between this speed of movement 416 of the drive element 403 and the
load 406 on the plunger 410. Indeed, once the speed of movement 416
of the drive element 403 is available, one can determine the
corresponding load 406 on the plunger by selecting from the stored
relationship the corresponding value either by computing when the
relationship is stored as a mathematical function or by retrieving
a corresponding value from a stored table of values or even by use
of more complicated computations as described further.
As the above methods when used for on-line control are executed in
real-time, those methods may be executed by electronic devices or
systems, which might be specifically designed for that purpose or
may be general-purpose electronic devices in combination with
instructions for carrying out the methods as described. As shown in
the flow chart of FIG. 3 a step 10 of obtaining, inputting,
measuring or sensing the speed of movement of one drive element
with the relevant means 404 is followed by a step 20 of determining
or computing a value 406 representative for or an estimate of the
load on the plunger 410 with the relevant means 431. This value 406
can then e.g. be displayed in the cabin of the baler operator.
Optionally one can determine 30 the maximum load 408 with the
relevant means 417 and e.g. display this maximum value 408. Or
optionally one determines 40 a control signal 405 to be applied to
at least one controllable element in the baler 420, e.g. by
comparing this maximum value 408 with the maximum reference value
409. The steps 20, 30 can be merged into one step 50. With a proper
model of the system, also the steps 20, 30 and 40 can be merged
into one step 60. Therefore the estimation method fits within
methods of determining a control signal for controlling the load on
a plunger 410 of a baler 420 and within methods for controlling the
load on a plunger 410 of a baler with at least one controllable
element 470 for controlling said load, steered by an actuator 440,
by applying the control signal to the actuator 440 of the
controllable element 470. It is to be noted that determining the
maximum value 408 of the load on the plunger 410 can be realized by
continuous use of the method (or at least performing sufficient
sampling) and storing the value if it is the highest observed so
far (with a refresh each cycle) or one can select a representative
sample time e.g. when the plunger 410 has reached its most rear
point or whatever other position considered representative.
As further shown in FIG. 3, one possible embodiment of the
invention includes a step 210 of filtering the obtained
measurements, e.g. by a low pass filtering, to avoid noisy signals.
As further shown in FIG. 3, the predetermined relationship can be a
static model 320, e.g. a linear (one- or multi-dimensional)
function. Also indicated in FIG. 3 is the possibility to feed in
agricultural material parameters 412 (either measured on-line e.g.
by means of a humidity sensor, or input by the operator). Indeed,
one may store multiple predetermined relationships--one for each
agricultural material condition--or may even use a
multi-dimensional function representation showing load on plunger
versus speed of the drive element and agricultural material
condition. In such embodiments the predetermined relationship is
selected in accordance with obtained agricultural material
characteristics of the agricultural material being baled by the
baler 420.
As shown in FIG. 7 there is a difference in behavior of the system
when an active cycle or passive cycle is considered. With an active
cycle is meant that the plunger is moving and compressing
agricultural material, while during a passive cycle agricultural
material is moved without substantially compressing it--there is
still some compression in such cycle due to expansion of the
material when the plunger retracts after an active cycle. FIG. 8
shows an alternative embodiment, wherein one selects 340 the
predetermined relation in accordance with the determined condition
330, being an active or passive cycle. Of course this embodiment
can easily be combined with embodiments feeding in agricultural
material characteristics. The determining of an active or passive
cycle can e.g. be determined based on measurements within the bale
chamber of the baler.
As indicated above the selection of the drive element to be used
for measuring and later determining the estimate of the load can be
done in view of the sensitivity of disturbing effects. As in such
balers the driving force, externally coming from the tractor
pulling the baler, has to supply force to the baler, the knotter
and/or the stuffer, typically such drive systems have a first sub
system 401, splitting the force of the baler plunger operations and
these other components, the force directed to the plunger then
being used in a second drive subsystem 402. In an embodiment of the
invention the selected drive element is part of the second drive
subsystem.
As the speed (and speed changes) changes with the net available
torque at the drive system (gearbox, flywheel), correcting the
predetermined relationship with possible influences thereon yields
a higher reliable method. Taking into account active or passive
cycles is one such correction. Taking into account whether the
other components like knotter and stuffer are actually operational
(and hence using some of the externally delivered force) and using
this information, e.g. again to select between a relationship in
one case and another relationship in the other case, is another
example of such a correction mechanism. In embodiments, the method
may then be further characterized in that the step of determining
the load of the plunger takes into account the indicative signal
(e.g. obtained via another sensor attached to such components)
related to the operation of those components. Both correction
mechanisms are compatible and even combinable with the use of
agricultural material characteristic information.
The relationship between the available torque (and hence the link
to the external force supplied by the tractor and the influence of
the other components like stuffer and knotter on this torque), the
dynamic effect of previous cycles, gravity and the load on the
plunger can be modeled by a set of mechanical equations, including
the load on the plunger and the velocities, e.g. of the
flywheel.
The relation between the torque to drive the plunger and the load
on the plunger is derived from the relations for the available
power at the gearbox Pg and the resulting power at the plunger
Pp.
The power at the gearbox is written as: P.sub.p=F{dot over (x)}
wherein F is the load on the plunger due to compression and moving
its own mass and {dot over (x)} is the velocity of the plunger in
m/s.
The available power at the gearbox is written as: P.sub.g=T{dot
over (.theta.)} wherein T is the available torque to drive the
plunger and {dot over (.theta.)} is the angular velocity of plunger
arm L1 (FIG. 4). The relation between the plunger position and the
angle of plunger arm L1 is given by: x=l.sub.1
cos(.theta.)+(l.sub.2.sup.2-(l.sub.3+l.sub.1
sin(.theta.)).sup.2).sup.1/2 wherein l1, l2 and l3 are the lengths
given in FIG. 4. This relation is derived with respect to time and
is then filled in, into the relation for Pp. When neglecting the
friction for driving the plunger, the power Pp at the plunger and
the power Pg at the gearbox are equal, and the load of the plunger
is calculated as:
.times..times..theta..times..function..theta..times..times..times..functi-
on..theta..times..function..theta..times..times..function..theta.
##EQU00001##
The connection between the rotation of the flywheel and the angular
rotation of arm L1 is fixed by the gears in the main gearbox.
Therefore, the rotation speed of arm L1 ({dot over (.theta.)}) is
immediately measured by the rotation speed of the flywheel.
In an alternative to the use of the static relationship (or
relationships plus relationship selection) described above, one can
build also on a dynamic model of the system under consideration, a
model-based estimator, based on principle of model-based control
theory. Such estimator feeds in a difference between the measured
velocity and a computed velocity and is designed in such a way that
the measured velocity and computed velocity converge to each other.
The load on the plunger can be considered as an extra parameter to
be estimated by the estimator. This embodiment is illustrated by
the flowchart of FIG. 9 which is similar to FIG. 8 except that step
20 comprises a step 370 of using an estimator based on a dynamic
model. The step 350 is a step where other baler system signals are
input and step 412 is a step where agricultural characteristics are
optionally input. The further advantage of this approach is that
the factors considered for correction in the static approach, here
can be included in a more natural way. Indeed the previous cycle is
part of the dynamics of the model while the external torque can be
made variable and hence dependent on the operations of the knotter
and stuffer. One might even include a simple compression model of
the agricultural material, to correct for the active-passive cycle
difference. Once the techniques of model-based control are used,
one can similarly construct the control signals based on such
model.
Aspects of the invention also provide for electronic device 431
used in a baler for determining an estimate of the load on a
plunger 410 of the baler, the electronic device being adapted for
executing any of the methods discussed above. Such electronic
device can be embedded in a system used in a baler, the system
comprising an electronic device 431 for determining a value
representative of or an estimate of the load on a plunger 410 of
the baler driven by a drive system 400 with at least one drive
element 403. The electronic device comprises a means (e.g. an input
port) for obtaining 10 the speed of movement of the drive element
403; a storage means (any storage or memory device) for storing
data about a predetermined relationship between the speed of
movement of the drive element 403 and the load on the plunger 410;
and a computation means (e.g. a CPU or dedicated data path in an
ASIC) for determining 20 the value representative of or the
estimate of the load on the plunger 410 based upon the obtained
speed of movement of the drive element 403 by use of the stored
predetermined relationship 220 between this speed of movement of
the drive element 403 and the load on the plunger 410. The system
may further comprise a sensor 404, operatively connected (wired or
wireless) to the electronic device 431 and used for measuring the
speed of movement of the drive element 403.
Aspects of the invention further provide for an electronic device
430 for determining a control signal for controlling the load on a
plunger 410 of a baler, adapted for executing control methods
described before. Such electronic device may be embedded in a
system further being adapted for determining a control signal for
controlling the load on a plunger 410 of a baler for harvested
agricultural material, the system comprising an electronic device
430, comprising the electronic device 413, a storage means (any
storage or memory device) for storing a reference maximum load of
the plunger 410 and computation (e.g. a CPU or dedicated data path
in an ASIC) means for determining 40 a control signal based on the
obtained value representative for or an estimate of the load on the
plunger 410 by use of a comparator for comparing the obtained value
representative of or an estimate of the load of the plunger 410
with the stored reference maximum load of the plunger 410. The
system may further be adapted for controlling the load on a plunger
410 of a baler, the system comprising: one controllable element 470
of the baler; and an actuator (hydraulic, pneumatic or electronic)
440, operatively connected (wired or wireless) to the controllable
element 470 for steering in accordance with the control signal.
The above-described method embodiments of the present invention may
be implemented in a processing system 1 such as shown in FIG. 10.
FIG. 10 shows one configuration of processing system 1 that
includes at least one programmable processor 13 coupled to a memory
subsystem 5 that includes at least one form of memory, e.g., RAM,
ROM, and so forth. It is to be noted that the processor 13 or
processors may be a general purpose, or a special purpose
processor, and may be for inclusion in a device, e.g., a chip that
has other components that perform other functions. Thus, one or
more aspects of the present invention can be implemented in digital
electronic circuitry, or in computer hardware, firmware, software,
or in combinations of them. The processing system 1 may include a
storage subsystem 12 that has at least one input port (e.g. disk
drive and/or CD-ROM drive and/or DVD drive). In some
implementations, a display system, a keyboard, and a pointing
device may be included as part of a user interface subsystem 9 to
provide for a user to manually input information. Ports for
outputting data also may be included. More elements such as network
connections, interfaces to various devices, and so forth, may be
included, but are not illustrated in FIG. 10. The various elements
of the processing system 1 may be coupled in various ways,
including via a bus subsystem 11 shown in FIG. 10 for simplicity as
a single bus, but will be understood to those in the art to include
a system of at least one bus. The memory of the memory subsystem 5
may at some time hold part or all (in either case shown as 4) of a
set of instructions that when executed on the processing system 1
implement the steps of the method embodiments described herein.
Thus, while a processing system 1 such as shown in FIG. 10 is prior
art, a system that includes the instructions to implement aspects
of the methods for determining a value representative for the load
on a plunger of a baler, or of the methods of determining a control
signal for controlling said load, or of the methods of controlling
said load is not prior art, and therefore FIG. 10 is not labeled as
prior art.
The present invention also includes a computer program or computer
program product which provides the functionality of any of the
methods according to the present invention when executed on a
computing device. Such computer program product can be tangibly
embodied in a carrier medium carrying machine-readable code for
execution by a programmable processor. The present invention thus
also relates to a carrier medium carrying a computer program
product that, when executed on computing means, provides
instructions for executing any of the methods as described above.
The term "carrier medium" refers to any medium that participates in
providing instructions to a processor for execution. Such a medium
may take many forms, including but not limited to, non-volatile
media, and transmission media. Non volatile media includes, for
example, optical or magnetic disks, such as a storage device which
is part of mass storage. Common forms of computer readable media
include, a CD-ROM, a DVD, a flexible disk or floppy disk, a memory
key, a tape, a memory chip or cartridge or any other medium from
which a computer can read. Various forms of computer readable media
may be involved in carrying one or more sequences of one or more
instructions to a processor for execution. The computer program or
computer program product can be carried on an electrical carrier
signal. The computer program product can also be transmitted via a
carrier wave in a network, such as a LAN, a WAN or the Internet.
Transmission media can take the form of acoustic or light waves,
such as those generated during radio wave and infrared data
communications. Transmission media include coaxial cables, copper
wire and fiber optics, including the wires that comprise a bus
within a computer.
* * * * *